1. Field of the Invention
The invention relates to the field of hydraulic oil storage tanks for vehicles, and more particularly, to a hydraulic oil storage tank for a vehicle which is incorporated in a vehicle headboard.
2. Prior Art
Many vehicles, especially trucks, require a hydraulic oil system for operating auxiliary hydraulic equipment. Since there are numerous varied applications for the hydraulic equipment on a vehicle, such vehicles are generally custom made for a particular intended application. The hydraulic oil system is usually a modification added to a generic vehicle by an aftermarket source after the vehicle is originally manufactured. The vehicle, for example a truck, is originally manufactured with engine and passenger compartments, and a frame which is suitable for further modification and can support a vehicle bed behind the passenger compartment.
A hydraulic oil system for a vehicle, for example a truck, has at least a hydraulic oil supply, a hydraulic oil pump and one or more actuators to be driven by hydraulic oil pressure. The pump can be electrical or driven via a power take-off from the vehicle main power source. The tank is preferably mounted close to the pump in order to minimize the length of connecting lines, need for connectors, and attendant fluid friction losses. Unless the tank is mounted above the pump, some means are required in order to provide a flooded suction reservoir at the pump inlet to decrease the tendency for pump cavitation.
The hydraulic oil supply is usually carried in a cylindrical tank disposed under a lateral side of the truck bed. The mounting location of the tank must often be chosen as a compromise of space restrictions, filling access requirements, connection lines and interference with other equipment on the vehicle. For example, it is undesirable to mount the tank on the vehicle bed, as this would reduce available cargo volume. However it is desirable to mount the tank above the pump for fluid supply purposes. The tank is generally hung below the frame, although space below the frame is limited by the need for other equipment such as a fuel tank or a third axle. Mounting the hydraulic tank below the frame limits the height (if any) by which the tank can be mounted above the hydraulic oil pump, and the connecting lines to and from the tank, the pump and the actuators may become excessively long.
The work applied to the hydraulic oil in pumping and in extraction of energy by the actuators, as well as conduction of friction produced heat to the oil, are such that the hydraulic oil in the tank becomes heated. The temperature of the oil can become quite high, due to concentration of the oil in one body and due to the proportionately lower surface area of a tank, available for cooling air circulation around the tank.
There is a need for a tank which mounts above the truck frame and the pump, using a minimum of space otherwise available for cargo volume, and providing increased cooling surface area.
By law, certain types of trucks are required to have a protective headboard separating the vehicle passenger compartment from the vehicle bed. The headboard may comprise a solid plate or a number of horizontal and vertical members joined together to form a rigid framework. The horizontal and vertical members may include tubing which is welded or otherwise joined together to form a structurally rigid barrier that is light in weight. The headboard provides a measure of safety for vehicle occupants by preventing a load on the vehicle bed from shifting forward towards the vehicle passenger compartment. The headboard is relatively large and necessarily takes up space at the front of the vehicle bed. While the headboard can be made from rectangular tubing to increase strength and rigidity per unit weight, the volume within the tubing remains unused. According to the invention, it is possible to utilize the volume within the tubing as part of the vehicle hydraulic oil system, with the simultaneous benefits of oil storage above the hydraulic pump, compact storage without using space beneath the truck bed, and if needed for cooling, increased tank surface area.